Electronic irrigation controllers have long been used on residential and commercial sites to water turf and landscaping. They typically comprise a plastic housing that encloses circuitry including a processor that executes a watering program. Watering schedules are typically manually entered or selected by a user with pushbutton and/or rotary controls while observing an LCD display. The processor turns a plurality of solenoid actuated valves ON and OFF with solid state.
A conventional irrigation controller of the type that is used in the commercial market typically includes a seasonal adjustment feature. This feature is typically a simple global adjustment implemented by the user that adjusts the overall watering as a percentage of the originally scheduled cycle times. It is common for the seasonal adjustment to vary between a range of about ten percent to about one hundred and fifty percent or more of the scheduled watering. This is the simplest and most common overall watering adjustment that users of irrigation controllers can effectuate. Users can move the amount of adjustment down to ten to thirty percent in the winter, depending on their local requirements. They may run the system at fifty percent during the spring or fall seasons, and then at one hundred percent for the summer. The ability to seasonally adjust up to one hundred and fifty percent or more of the scheduled watering accommodates the occasional heat wave when turf and landscaping require significantly increased watering. The seasonal adjustment feature does not produce the optimum watering schedules because it does not take into consideration the amount of moisture that is actually available in the soil for the plants to utilize for healthy growth. Instead, the seasonal adjustment feature is manually set to simply adjust the watering schedules globally to run a longer or shorter period of time based on the existing watering schedule. When the seasonal adjustment feature is accurately re-set on a regular basis, a substantial amount of water is conserved while still providing adequate irrigation in a variety of weather conditions. The problem is that most users do not re-set it on a regular basis, or do not set it correctly, so a considerable amount of water is still wasted, or turf and landscaping die.
In the past, irrigation controllers used with turf and landscaping have used Soil moisture data to activate or deactivate irrigation zones based on actual soil moisture conditions. When soil moisture sensors are used with conventional irrigation controllers the sensors typically interrupt the programmed irrigation cycle by breaking the electrical connection between the controller and the irrigation valves when the soil is moist. Some specialized controllers that are designed to work specifically with soil moisture sensors can turn the irrigation on when the soil reaches a dry state, then turns the controller off when it reaches a moist state.
While conventional soil moisture based controllers help to conserve water and maintain plant health over a wide range of weather conditions they are specialized to the soil moisture sensor control and may not meet other needs of the landscaped area well. Soil moisture sensors that are hooked up to traditional irrigation controllers may simply disrupt the scheduled irrigation by disconnecting the common line to the valves when the soil is moist. In these cases, the irrigation controller turns on the outputs to the valves when they are normally scheduled to run. If the soil moisture sensor is sensing moist soil conditions, it simply disconnects the electrical circuit to the valve. The controller thinks it is irrigating, but the irrigation process is not happening. This can create confusion for the user when they go to the controller and see that station (X) is on yet they go out to the property to see that the same station is not running irrigation. This can result in calls to professionals to debug the system when the soil moisture was just keeping the station from running as designed. In these applications, there is no indication on the controller that the soil moisture has disrupted the irrigation process. In both of the above circumstances, the systems may require one sensor to be placed in the ground for every zone on the controller. Cables are then run back to the controller through the landscape. Some irrigation controllers, such as the ACC controller from Hunter Industries, can control forty-eight zones of irrigation. This requires up to forty-eight sensors to be placed in the ground with forty-eight cables buried throughout the landscape area and run back to the controller. This requires a substantial cost in materials and labor. Additionally, some conventional irrigation controllers may calculate the amount of water used based on the irrigation cycles as they run. When the sensors disrupt irrigation, while the controller thinks it is irrigating, the controller creates erroneous reports of over use of water, when in fact conservation is occurring. In some irrigation controllers, the controller knows the theoretical amount of water scheduled to be applied. As the stations are running, the controller measures this theoretical flow against the actual flow with a flow meter installed on the irrigation site. When the theoretical and actual flow is not within certain parameters, an alarm will indicate that there is a problem with the irrigation system. Soil moisture installations mentioned above will not work with these types of controllers. Another application is where one soil moisture sensor is hooked up to a rain sensor port on the conventional type of irrigation controller. In this case, as soon as the sensor senses moisture, it shuts the entire controller off. This requires very abnormal programming in the controller and also requires the sensor to be placed in the last station to be run so the irrigation does not shut off before all stations have irrigated. With this arrangement, the programming of the controller is very important as all of the previous stations may have run too much water for proper irrigation to have occurred prior to the last station sensing that the soil is moist after just a few minutes of irrigation.